[native/keyserver] add source param on log in from native

Summary:
Add indication if login comes directly from native UI.

Additionally: I moved spreading ...extraInfo, to the first place because I believe it's unsafe (it might override some important fields when extraInfo will change).

Test Plan:

1. Log request input here
2. Log in from the native app
3. Check if the source was properly received

Reviewers: tomek, atul, ashoat

Reviewed By: ashoat

Subscribers: ashoat, atul, abosh

Differential Revision: https://phab.comm.dev/D5258